Some accessories for internal combustion engines, especially such accessories as nitrous oxide injection systems and other engine performance enhancing devices, typically require triggering or operation of these systems only at certain engine speeds or fuel feed conditions, such as at full throttle. It is known in the art to provide triggering via mechanical attachments, such as mechanical attachment of a switch or other activation device to a throttle lever or accelerator pedal.
Many modern cars also provide for control of various engine and other functions using computer and electronic systems and devices. These systems typically include various sensing or output connections for providing such output as variable voltages or currents corresponding to driven functions.
One problem with using such outputs as the throttle position sensor (TPS) for an internal combustion engined vehicle or other sensed voltage locations for vehicles is that such locations are typically sensitive to current loading. For example, the TPS has an output voltage that reflects the voltage of the system used to control vehicle engine operation, which occurs through relatively sensitive electronic and computer control components. As a result, placing a high load, such as a low resistance resistor or other component, between the TPS and ground may cause a high current draw from this voltage source, potentially affecting computer or other circuit operation by reducing effective current or voltage available to those components. In addition, depending on the particular computer or circuit layout for the engine, it is possible that the high current may be drawn through the computer or circuit for the engine, potentially producing a failure of those components.
Further, by altering the current or voltage level available to the computer or other circuit for the engine, other engine components or engine performance may be significantly altered, producing such unwanted results as overrevving of the engine or producing an engine speed much below the expected speed for a given output voltage, potentially resulting in engine damage or failure.
Another problem with using such output as the sensed TPS voltage for triggering, for example, a nitrous oxide system is that variation exists between car models in the output voltage at the TPS for full throttle. Typically, in an application such as a trigger for a nitrous oxide kit, nitrous oxide must be fed via a switch mechanism only at full throttle conditions. However, some cars have full throttle at a high voltage condition, while others have full throttle at a low voltage. For example, in some cars, throttle position sensor voltage varies from a low of about 0 volts at idle to about 5 volts at full throttle, while other cars have an idle voltage of 5 volts with a full throttle voltage of 0 volts. Further, the range of voltage levels is variable. The high voltage may be 4 volts, 5 volts, 6 volts, or 10 volts, for example.
Accordingly, there is a need for a simple, reliable, and relatively current insensitive device, method, and system for allowing simple installation and trigger setting for an engine performance accessory item, such as a nitrous oxide injection system. There is a further need for a device, method, and system that allows flexible setting for both high and low voltage full throttle conditions and for a range of voltages or other electrical output at full throttle or at other selected engine conditions. There is a further need for such a device, method, and system that requires little current or power draw from the sensed source for the trigger. There is yet a further need for a device, method, and system that is easily installed and adjusted by a single user.